1. Field of the Invention
The present invention relates to new chemically-amplified positive photoresist compositions that contain a photoactive component and a blend of at least two distinct resins: i) a first resin that comprises carbocyclic aryl units with hetero substitution (particularly hydroxy or thio) and ii) a second cross-linked resin. Preferred photoresists of the invention can be imaged at short wavelengths, such as sub-200 nm, particularly 193 nm.
2. Background
Photoresists are photosensitive films used for transfer of images to a substrate. A coating layer of a photoresist is formed on a substrate and the photoresist layer is then exposed through a photomask to a source of activating radiation. The photomask has areas that are opaque to activating radiation and other areas that are transparent to activating radiation. Exposure to activating radiation provides a photoinduced chemical transformation of the photoresist coating to thereby transfer the pattern of the photomask to the photoresist-coated substrate. Following exposure, the photoresist is developed to provide a relief image that permits selective processing of a substrate. See Deforest, Photoresist Materials and Processes, McGraw Hill Book Company, New York, ch. 2, 1975 and by Moreau, Semiconductor Lithography, Principles, Practices and Materials, Plenum Press, New York, ch. 2 and 4.
Interest has increased in photoresists that can be photoimaged with short wavelength radiation, including exposure radiation of less than 200 nm, such as wavelengths of about 193 nm. Use of such short exposure wavelengths can enable formation of smaller features. Accordingly, a photoresist that yields well-resolved images upon 193 nm exposure could enable formation of extremely small (e.g. sub-0.25 μm) features that respond to constant industry demands for smaller dimension circuit patterns, e.g. to provide greater circuit density and enhanced device performance.
New photoresist components such as resins and photoacid generators have been investigated to improve lithographic performance. See, for instance, U.S. Patent Publications 2002/0012869 and 2004/0038150, which disclose highly useful photoresists.
Nevertheless, efforts continue to improve lithographic properties of photoresists, including for high performance applications such as to print features having dimensions less than 0.2 or 0.1 microns. In such high performance applications, problems may occur such as undesired line edge roughness of the developed resist image and limited depth of focus problems, among others. See, e.g., U.S. Patent Publication 2004/0053511.
It thus would be desirable to have new photoresist compositions. It would be particularly desirable to have new photoresist compositions that could provide good resolution in high performance applications, such as to form imaged resist features having dimensions of about 0.2 microns or less.